I can only remember him calling her Brennan once and that was in Headless Witch in the Woods (S2)...It was where Cam suddenly figures out that it was the brother of the victim who was the murderer...Bones is currently on a dinner date with him...Booth says 'Brennan is with him right now' and tears off to find her...In this instance he was worried! I will try and recall if he ever called her Brennan any other time...
Awww, cute! But he's referring to her as Brennan while talking to someone else, which I think he does whenever he's talking to someone outside of the squints. I was wondering if he's ever actually told her to her face, "Look, Brennan..." the way he'll tell her, "Look, Bones, I think that...etc" But thanks though